The present invention relates generally to fluid seal, and more particularly, to a specialized type of fluid seal adapted to provide multiple functions in use, and to do so at low cost with a high degree of reliability.
In recent years, there has been a definite trend in the automotive industry towards manufacturing engine and driveline components of increasing compactness and complexity. With constantly increasing emphasis being placed on increased economy of operation, the automotive industry has responded by making most of its automobiles smaller, lighter and more compact. This, in turn, has created the need for smaller but "harder working" engines, and the contemporaneous requirements of holding automotive emissions to an absolute minimum has further occasioned the manufacture of engines which are required to contend with very high operating temperatures.
At the same time that the foregoing trends have been in evidence, there has been an additional trend, particularly because of the high cost of labor, to reduce scheduled engine and chassis maintenance to an absolute minimum. Consequently, it is not unusual for automobiles of today to have recommended oil change intervals ranging from 4,000 to perhaps 7,500 miles between changes. Industry, in some cases, specifies synthetic oils or those having special additive packages which can accommodate lengthened intervals between changes and still provide the numerous functions required of lubricants forced to operate under severe conditions.
As a result of the infrequent scheduling of oil changes, in effect, a premium has been placed on ensuring that the crankcase oil in an automobile is maintained at a proper level between changes. Since the extended oil change intervals may, in effect, occasion an attitude of neglect or at least less frequent checking on the part of the automobile owner, the importance of ensuring that the oil level does not fall below critical limits is emphasized even further, it being recognized that severe, expensive engine damage may result from a lubrication failure occasioned by low crankcase oil levels.
An approach recently followed by some auto designers, therefore, has been to provide not only oil pressure sending units of the conventional type, but to include oil level indicator sending units in the oil pans of engines to insure that even neglectful owners are not victimized by serious engine damage occasioned by low oil levels in the use of their vehicles.
According to the present invention, a novel oil seal for an oil level indicator sending unit is provided which will serve a number of functions. By way of further background, it will be realized that, unlike a simple oil pan drain plug, same oil level indicator sending units are, in effect, a combination mechanical plug and electrical instrument, and consequently, it is not always preferred to attempt to ensure against oil leakage merely by applying an extremely strong sealing torque to the unit. In some case, however, the installation torque may be very high. Consequently, there has been a need for a seal unit which will accomplish several objects in use, among them being reliability and leakproof performance, whether the installation is made into a sheet metal or a cast aluminum part such as an oil pan.
In addition, there has been a need for a seal which may be positioned as desired over the oil level indicator sending unit or other instrument prior to installation so as to eliminate the need for prealignment and to reduce the likelihood that the seal may be placed in an improper position prior to installation and tightening.
Another need has been to provide a seal which will accommodate dimensional and torque value variations within a given installation and still provide the necessary fluid-tight seal; there is quite clearly also a need to accomplish the foregoing objectives at a reasonable price.
Accordingly, it is the primary object of the present invention to provide an improved oil seal unit for installation between mating parts and characterized by improved versatility in use.
Another object of the invention is to provide an oil seal which provides at least one, and preferably a plurality of elastomeric ribs or like formations adapted to be trapped between opposed end faces of parts to be sealed.
A further object of the invention is to provide a seal which may be positioned relative to, and retained on, one of the two parts until the assembly operation has been completed.
Yet another object of the invention is to provide a seal unit which includes a casing and an elastomeric seal body having several functional portions, one providing a pair of end face seals, another providing a cavity or recess filling function, a third portion providing a seal retention feature, and another portion insuring that the seal casing does not move radially relative to the body of the sealing unit during installation.
A still further object of the invention is to provide a seal which optionally includes a flanged casing adapted to protectively surround a part of the installed sending element.
A further object is to provide a combination sending unit, oil pan and seal unit capable of reliable performance.
Yet another object of the invention is to provide a seal unit which may be made with existing technology but which provides multiple functions in use and which is consistent with existing installation technology.
A still furhter object is to provide a seal wherein the rubber element is strongly bonded to the casing to avoid displacement even under high torque conditions of installation.
The foregoing and other objects and advantages of the invention are achieved in practice by providing an oil seal adapted to be disposed between portions of mating parts which have opposed end face surfaces and in which the seal unit includes a casing having bonded thereto an elastomeric body with inner, outer and intermediate portions each adapted to provide a specialized sealing and/or locating and positioning function in the use of the seal.
The manner in which the foregoing and other objects and advantages of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiment of the invention set forth by way of example and shown in the accompanying drawings, wherein like reference numbers indicate corresponding parts throughout.